Method of making heat interchange apparatus



J. V. CARON Dec; 25, 1945.

METHOD OF MAKING HEAT INTERCHANGE APPARATUS Filed Aug. 25. 1942 Patented Dec. 25, 1945 ifMarn onon- MAKING HEAT INTERGHANGE APPARATUS Josesnwimrcmnmaveimuemass. Appllcationrmigust 25, IQAZQSeriaLNmASSQSS This invention relatestto theimanufa'ictureuof heat interohangezapparatus;such; fomexamp'le, as internal: combusfionengines and compressiomcylinders. and the like; :and more: particularly where the :heatrinterchange; is: prod-ucedqby providing 1; relativeiythinifins: projectingzfrom'a icylinderjor 'the like: about which a current Ofaairnrrotheltsas :isrzaused' to flow.

\Ite'is weilr-tknownithat .certair1::meta1s arefmuch v more e'fiicient as rheat 'acondu ctorsrthan mothers,

, and because iron ;or :othersferrous xmaterial: is

:much inferior into copper in .heat conductivity.

For these reasons it has become customarycto nfo-rm renginex and' compressor=. cy1inders iasasteel iorsalloyfforgings "and: then; to rcutnsl'otssinwardly,

..-iron=: contacts. rwliilesurface :melting: and: fusion wssential: :order to -sefiect :a welding 1 of the fimand bodyjportionsstogetherlsothat heat conductivity=betweenithem whendn= use may be rapid, ihiemusttnot be-allowed toggoeso far: as to melt roffi the"coppercontactedsiby molteniiron f -Jth8 remainder :Of'Ltihe copper element. The ap- ;;plication of -.;this?method to icopper rfins for cast iron ricylindersi-isa most important one, but i this ziinventionzis also applicablezxto other-situations whereiitmayanot be desired to; use metals having esuchi'difierent :melting points as copper andcast :iron. wEor exampledn-some cases. sufficient coo1- cingi maybe afforded zbyi -thesuse oftsoft: steel fins ztpmjecting from a cast-iron cylinder or there may the iotherzcombinations of;.a11cys-,such-- as the alui and magnesium-:alloysnow iemployed'ior "internal: combustion rain-craft or other :engines for" theucylindersr :and cylinder heads.

:For a more 3 complete understanding of n this 'inventiom reference rmaybe had .to'i-the raccompanying drawing in which uaFigure'hl-eisr a; perspective :view of a cast =twocylinder-1 Lhead. internal combustionsengine block A leavingsintegral' finslbetweenathecuts. aThi'seisz-an *fifiyrprovided mitmsheeumetal .cooling fins and made expensive procedure sandttherfinszibeingtmaderof tithe steeltor; alloy are inieriot nt heaticonducting qualities to? copper fins.

it hasz'been::attempted; therefore;::tos pre-form sin saccordance: withtth-isfinvention.

.-.1-;Eigure izz is a-fiperspective 'view Diva two part 'matterm'for the barrel portion of a; single cylinder :rblock t the partsxof the ipattern beingislightly. sep- :fins 56f cepper Wort alloysz'ofmopper: andto cast a arated.

the teaching' of tinsifinv'ention tielicarefullyifollowed; with relatively small rejections on acc'ount :ofiimperfect casting; By so doingyndm'achining cfthe outside of the cylin deror block to produce f fins is required; and desired the: hea'dfmay be formed integral with thetcylindenthus avoiding the necessity of machining and securingzrth'ese parts; together. -It will be noted thatithezrmolten 1 iron when i cast will have a .;temperature iinlrthe {Figure 3 ism; perspeetivewievcshowing a twoxpart sheetrmetal fin. V

.-;Figure -.=;4 '11s 2,9, iragmentary vertical section -.\through:1a .zflask :and::=mo1d showing the pattern r935 of Figure 2 andrifins likethe showing: of Figure 3 position; therein. 1 si'igureSeneca view similar to Figure-4, but showing:.-.1the;;:2pattern removed and 2 the ,;core=.-in :p1ace, ithe #mold :being ready: fo-r1.pouring.

Figure 6 is a crossrsectional view on 1ine:-6-5 of tf.igurez5.

eFigures Tand- =8 arezxfragmentaryzsectional views cshnilarsto portions:of:Figures: 41am 5 but showaiing zattmodification lwhereinnther rfinsi-are closely 315 spaced.

:FigureiQmis: at? fragmentary-side elevation-oft a '-cylin der::foraa talvezin head-engineiandfinned in iaccordance-xwithzthis; invention.

L:Eigure#:1Oakcamelevation of a single. cylinder I neighborhoodof 2800 B; and the melting point; fihaizingsamintegralrhead.

I of copper is much lowenaround 1'950? F.;:so that *When -a mass of I this molten iromccntact'smith the preformedi copper fins, "unless the" heat from iro-n c'an he quicklyidissipated,iit wilr melt ."1 In Figure; iron-the; accompanying :drawing is shown two cylinders cast in a block for-.-an L "tl'iead eintemal combustion engine. These swill li'ordinarilyi belcastrin two sections; onehcomprisiithg copper tportiomawim thexmblteni;.mizmgithelbanels It Ofithe "cylindersriand. the housthe present invention may well be formed of sheet metal of any desired composition.

In Figure 2 is shown a pattern for the barrel of a single cylinder. This pattern is formed in upper and lower parts Ill and II, each-ofwhich is provided at its ends with the core prints I2 and I3 which are of smaller external "diameter" than the remainder of the pattern. Along the barrel portion of the pattern there are provided outwardly projecting parallel beads or ribs I5 which may be substantially semi-cylindrical in outline,- these being arranged spaced apart in accordance with the desired spacing of the fins. Each of these beads is provided with a central roove I6 of suificient size to admit the inner edge of the pre-formed fin, such as is shown detached in Figure 3. These fins are formed as annular half sections to correspond with the halves of the pattern and they may be Well formed of sheet metal of the particular material desired for cooling. For example, in the body of the cylinder they may beformed of soft steel, or if greater cooling effect is desired, they may be formed of copper. Preferably they are formed with perforations as at [1, it being found in practice that such perforations tend to cause more effective cooling action of the air which comes in contact with the fins. They also may serve a desirable purpose in assembling the pattem with the fins thereonin the mold as will later appear.

The fins are assembled on the pattern parts with their inner edges inserted in the grooves I6 of the beads' I5 and rods or bars I8 inserted through alined holes Il may be employed to facilitate assembly of these parts. The two parts of the pattern with the fins and rods or bars thus assembled therewith are then employed to make a green sand mold in the cope and drag of the flask in the well known manner. These fins and the rods or bars remain in 'the green sand mold but said rods or bars are removed from the fins after the casting operation and after the castings are taken from the mold.

The method of molding a plurality of cylinders in block is the same as for individual cylinders, except that the fins may be continuous for the full number of cylinders but made in halves, one half for each part of the pattern.

Where the fins are made of copper it may be found desirable to employ molding sand somewhat more moist than in the ordinary practice of casting iron, but this should not be sufficiently moist to cause blowing of the casting during pouring. However, due to the high conductivity of the copper, such additional moisture provides additional cooling efiect to the fins, helping to prevent them from becoming melted off by the great heat of the molten iron, the melting temperature of which is considerably higher than that of the copper.

When the pattern is drawn from the green sand mold, the fins are left embedded in said mold, with their inner edges projecting into the recesses I9 in the outer wall of the mold cavity 20, these recesses having been formed by the presence of the beads I5 of the mold. When the core 2| is now placed in position and the mold reassembled, said mold is ready for pouring. The recesses I9 in the outer wall of the mold cavity form beads in the cast cylinder corresponding to the pattern beads, within which the inner projecting edges of the fins are embedded, and these beads thus form restricted masses of the molten metal which are cooled rapidly by the heat conducted away therefrom by the fins so that they become cooled and solidified earlier than the mass of the metal in the main mold cavity 20. Thus the fins are not subjected to the full action of the high temperatures of the molten metal of the whole mass, this further acting to prevent the fin edges from becoming melted oil from the remainder of during the casting operation in such a manner that the fiow of molten metal takes place along the side faces of the projecting portions of the fin rather than crosswise thereof. as any cross flow would tend to Wash 011 the projecting portions of the fins and thus destroy their attachment to the cast cylinder. This may be done by providing sprue holes such as 25 which extend down to the lower portion of the drag I I and are gated to the mold cavity 20 from beneath as at 26, the mold also being provided with suitable risers as 21 to provide vents and insure that the mold cavity is entirely filled through the hydrostatic pressure ofv the molten metal in the mold. With this arrangement the molten metal rises from the bottom of the mold cavity upward in linewith the fins, and the mold should be poured from .a suflicient number of points so as to insure even heat distribution throughout the mold cavity.

In some instances it may be found desirable to I space the fins very closely for additional cooling effect, as, for example, in the combustion chambers of internal combustion engine cylinder heads. Where thisis desired it may be unnecessary to employ the projecting beads within which the inner edges of the fins are embedded even if there :were room for'such beads, this being for the reason that with the increased number of fins in a given space, the heat conduction is so rapid that the surface portion of the casting is sufilciently quickly chilled as to prevent the possibility of the fins being melted off by the mass of metal. Such an arrangement is shown in Figures 7 and 8.

- Figure 7 showing the pattern 30 being provided to the cast iron of the completed cylinder.

with grooves 3I.to receive the fins 32, the depths of these grooves defining the amounts by which the edges of the fins will project into the mold cavity 28 of the mold as shown in Figure 8. This arrangement of the fins corresponds to the show-- wall thickness of 9:; inch, beads 3% of an inch in diameter grooved to a depth of of an inch, and copper fins of a thickness .015 inch, one inch in width and arranged five to each inch of cylinder length, will ordinarily be found satisfactory. With larger or smaller sizes of cylinders, the proportions will, of course, be modified accordingly, but with this as a guide the skilled foundryman should find no difiiculty in proper proportioning the parts to insure welding of copper fins to cast iron and without melting off the copper fins. If lighter Weight cylinders are desired semisteel or the lighter weight alloys may be substituted for the cast iron with appropriate changes in other factors.

In cases where very thin fins are desirable, they may be protected from being melted off by the molten cast iron by coating them previous to casting in the mold with protective compounds which act to delay actual contact of the molten iron with the fins and thus delay the full application of the heat from the molten iron to said fins, but do not prevent sufiicient ultimate contact to prevent the desired welding of the fins to the cast iron. For example, such a composition may be formed of lead oxide, together with about a third as much graphite mixed with a heat-resistant oil, or fire clay, with or without graphite, and mixed with water or oil, may be used. The amount of such a composition to be added in any particular case may be determined by experimentation, it being understood, however, that considerable leeway is permissible while obtaining good results, and when determined for one particular set of conditions may be readily duplicated for the same conditions. Likewise the amount of moisture of the sand mold, which in the case of copper fins is preferably somewhat greater than in usual iron foundry practice, having once been determined, may be maintained satisfactorily. Here, again, there is considerable leeway, provided the pouring temperatures are maintained substantially uniform as may be done in commercial foundr practice.

In Figure 10 is shown a single cylinder with integral head and provided with fins 35 cast in in accordance with this invention on both the cylinder side wall and the head.

From the foregoing description of this invention it should be understood that various other modifications and changes may be made without departing from the spirit or scope of this invention.

I claim:

1. In a method of manufacturing a finned body with the aid of a molding flask having a drag and a cope; the steps of constructing a plurality of semi-circular fin halves; forming a green sand mold section in said drag with half the number of said fin halves embedded in said mold section and projecting into the mold cavity; forming a second green sand mold section in said cope with the remainder of said fin halves embedded in this mold section and projecting into the mold cavity; assembling said green sand mold sections, with the fin halves held by one sectionin end-toend abutting relation with the fin halves held by the other section; pouring molten metal into the complete fin-holding mold; and removing said mold, leaving the cast body with'attached fins.

2. In a method of manufacturing a finned body with the aid of a molding flask having a drag and a cope; the steps of constructing a pattern divided into a drag half and a cope half and having circumferential grooves; constructing a plurality of semi-circular fin halves; placing the inner peripheral edge portions of half the number of said fin halves in the grooves of said drag half of said pattern; placing the inner peripheral edge portions of the remainder of said fin halves in the grooves of said cope half of said pattern; with the aid of said drag, said drag half of said pattern, and the fin halves carried by the latter, forming a green sand mold section; with the aid of said cope, said cope half of said pattern, and the fin halves carried by the latter, forming a complementary green mold section; withdrawing said pattern halves from said green mold sections and the fin halves embedded therein, leaving said fin halves with their inner peripheral edge portions projecting from said green sand mold sections into the mold cavities thereof; assembling said green sand mold sections with the fin halves held by one section in end-to-end abutting relation with the fin halves held by the other section; pouring molten metal into the mold; and removing said mold, leaving the cast body with said fins attached thereto.

3. In a method of manufacturing a finned body with the aid of a molding flask having a drag and a cope; the steps of constructing a plurality of semi-circular fin halves; supporting half the number of said fin halves in said drag in spaced relation with each other; packing green sand'in said drag and between the fin halves therein to form a green sand mold section in said drag with said half the number of said fin halves embedded in said mold section and projecting into the mold cavity; supporting the remainder of said fin halves in said cope in spaced relation with each other; packing green sand in said cope and between the fin halves therein to form a second green sand mold section in said cope with said remainder of said fin halves embedded in this mold section and projecting into the mold cavity; assembling said green sand mold sections and placing said fin halves held by one section in end-to-end abutting relation with said fin halves held by the other section: pouring molten metal into the complete fin-holding mold; and removing said mold, leaving the cast body with attached fins.

JOSEPH VICTOR CARON. 

